Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual sistema de combustível o modelo de motores a diesel possui?
 ###Tabelas: CREATE TABLE soundtrack (soundtrack_id AUTO_INCREMENT PRIMARY KEY, Year INT, Song Title VARCHAR, Artist VARCHAR, Genre VARCHAR, Original Game VARCHAR, Band Tier/Venue VARCHAR, Exportable to GH5/BH VARCHAR) CREATE TABLE engines (engines_id AUTO_INCREMENT PRIMARY KEY, Model VARCHAR, Engine VARCHAR, Displacement VARCHAR, Valvetrain VARCHAR, Fuel system VARCHAR, Max. power at rpm VARCHAR, Max. torque at rpm VARCHAR, Years VARCHAR) CREATE TABLE main_issuers (main_issuers_id AUTO_INCREMENT PRIMARY KEY, Currency VARCHAR, Country VARCHAR, Generic Name or Nickname VARCHAR, Rating ( S&P / Moodys ) VARCHAR, Negotiable debt at mid-2005 ( US dollar bn equivalent) INT, Government financial liabilities as % of GDP (end 2003 - source : OECD ) VARCHAR, Issuer VARCHAR, Internet site VARCHAR) CREATE TABLE 1914 (1914_id AUTO_INCREMENT PRIMARY KEY, meas. num INT, passed VARCHAR, YES votes INT, NO votes INT, % YES VARCHAR, Const. Amd.? VARCHAR, type VARCHAR, description VARCHAR) CREATE TABLE women's_doubles_performance_timeline (women's_doubles_performance_timeline_id AUTO_INCREMENT PRIMARY KEY, Tournament VARCHAR, 2009 VARCHAR, 2010 VARCHAR, 2011 VARCHAR, 2012 VARCHAR, 2013 VARCHAR)  
SELECT Fuel system FROM engines WHERE Model = diesel engines